document_title: List of Family Guy episodes

question_text: how many series of family guy is there

question_tokens: how many series of family guy is there

root

text: List of Family Guy episodes

text: Family Guy is an American animated television sitcom created by Seth MacFarlane for the Fox Broadcasting Company. The series centers on the dysfunctional Griffin family, which consists of father Peter (MacFarlane), mother Lois (Alex Borstein), daughter Meg (Lacey Chabert in episodes 1–9, then Mila Kunis in "Da Boom" onwards), son Chris (Seth Green), baby Stewie (MacFarlane) and Brian (MacFarlane), the family dog. The show is set in the fictional town of Quahog, Rhode Island, and lampoons American culture, often in the form of cutaway gags, and tangential vignettes.

tag: p

text: The concept of Family Guy was conceived by MacFarlane in 1995 while studying animation at the Rhode Island School of Design. He created two shorts entitled The Life of Larry and Larry & Steve, both of which played a key role in Fox executives' decision to pick up the series in 1998. After two seasons, Fox decided to cancel the show. Despite the cancellation, a third season was produced,[1][2] after which the series was officially cancelled at the end of 2003. Reruns on Cartoon Network's block Adult Swim drove up interest, and a letter-writing campaign, along with impressive DVD sales, encouraged Fox to bring the show back permanently.[3]

text: Family Guy and its cast have been nominated for twenty-three Primetime Emmy Awards, winning six. MacFarlane won the Outstanding Voice-Over Performance award for his performance as Stewie,[4] MacFarlane and Walter Murphy won the Outstanding Music and Lyrics award for the song "You Got a Lot to See" from the episode "Brian Wallows and Peter's Swallows",[4] Steven Fonti won the Outstanding Individual Achievement in Animation award for his storyboard work in the episode "No Chris Left Behind",[5] Greg Colton won the Outstanding Individual Achievement in Animation award for his storyboard work in the episode "Road to the Multiverse",[6] Patrick S. Clark and Jim Fitzpatrick won the Outstanding Sound Mixing for a Comedy or Drama Series (Half-Hour) and Animation award for their sound mixing work on the episode "Road to the North Pole",[7] and MacFarlane won the Outstanding Character Voice-Over Performance award for his performances on the episode "Pilling Them Softly".[8] The show was nominated for twelve Annies, and won three times, twice in 2006 and once in 2008.[9][10][11] In 2009, it was nominated for an Emmy for Outstanding Comedy Series, becoming the first animated program to be nominated in this category since The Flintstones in 1961.[12]

text: As of May 21, 2017[update], 289 episodes of Family Guy have aired, concluding the fifteenth season. The series remains Fox's second-longest-running program, behind The Simpsons[13]. It was renewed for a sixteenth season in May 2017.[14] The season is scheduled to premiere on October 1, 2017,[15] and will also contain the series' 300th episode.[16]

text: Seasons: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Unscheduled episodes Specials Home media References

tag: table

text: Series overview[edit]

text:
Season
Episodes
Originally aired
Nielsen ratings

First aired
Last aired
Rank
Viewers
(in millions)

1
7
January 31, 1999 (1999-01-31)
May 16, 1999 (1999-05-16)
33
12.80[17]

2
21
September 23, 1999 (1999-09-23)
August 1, 2000 (2000-08-01)
114
6.32[18]

3
22
July 11, 2001 (2001-07-11)
November 9, 2003 (2003-11-09)
125
4.50[19]

4
30
May 1, 2005 (2005-05-01)
May 21, 2006 (2006-05-21)
68
7.90[20]

5
18
September 10, 2006 (2006-09-10)
May 20, 2007 (2007-05-20)
71
7.20[21]

6
12
September 23, 2007 (2007-09-23)
May 4, 2008 (2008-05-04)
84
7.94[22]

7
16
September 28, 2008 (2008-09-28)
May 17, 2009 (2009-05-17)
69
7.56[23]

8
21
September 27, 2009 (2009-09-27)
June 20, 2010 (2010-06-20)
53
7.73[24]

9
18
September 26, 2010 (2010-09-26)
May 22, 2011 (2011-05-22)
56
7.66[25]

10
23
September 25, 2011 (2011-09-25)
May 20, 2012 (2012-05-20)
63
7.30[26]

11
22
September 30, 2012 (2012-09-30)
May 19, 2013 (2013-05-19)
62
6.94[27]

12
21
September 29, 2013 (2013-09-29)
May 18, 2014 (2014-05-18)
78
6.11[28]

13
18
September 28, 2014 (2014-09-28)
May 17, 2015 (2015-05-17)
94
5.86[29]

14
20
September 27, 2015 (2015-09-27)
May 22, 2016 (2016-05-22)
111
4.28[30]

15
20
September 25, 2016 (2016-09-25)
May 21, 2017 (2017-05-21)
116
3.93[31]

16
TBA
October 1, 2017 (2017-10-01)
TBA
TBA
TBA

text: Episodes[edit]

text: Season 1 (1999)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code

1
1
"Death Has a Shadow"
Peter Shin
Seth MacFarlane
January 31, 1999 (1999-01-31)
1ACX01

2
2
"I Never Met the Dead Man"
Michael Dante DiMartino
Chris Sheridan
April 11, 1999 (1999-04-11)
1ACX02

3
3
"Chitty Chitty Death Bang"
Dominic Polcino
Danny Smith
April 18, 1999 (1999-04-18)
1ACX04

4
4
"Mind Over Murder"
Roy Allen Smith
Neil Goldman & Garrett Donovan
April 25, 1999 (1999-04-25)
1ACX03

5
5
"A Hero Sits Next Door"
Monte Young
Mike Barker & Matt Weitzman
May 2, 1999 (1999-05-02)
1ACX05

6
6
"The Son Also Draws"
Neil Affleck
Ricky Blitt
May 9, 1999 (1999-05-09)
1ACX06

7
7
"Brian: Portrait of a Dog"
Michael Dante DiMartino
Gary Janetti
May 16, 1999 (1999-05-16)
1ACX07

text: Season 2 (1999–2000)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code

8
1
"Peter, Peter, Caviar Eater"
Jeff Myers
Chris Sheridan
September 23, 1999 (1999-09-23)
1ACX08

9
2
"Holy Crap"
Neil Affleck
Danny Smith
September 30, 1999 (1999-09-30)
1ACX11

10
3
"Da Boom"
Bob Jaques
Neil Goldman & Garrett Donovan
December 26, 1999 (1999-12-26)
2ACX06

11
4
"Brian in Love"
Jack Dyer
Gary Janetti
March 7, 2000 (2000-03-07)
2ACX01

12
5
"Love Thy Trophy"
Jack Dyer
Mike Barker & Matt Weitzman
March 14, 2000 (2000-03-14)
1ACX13

13
6
"Death Is a Bitch"
Michael Dante DiMartino
Ricky Blitt
March 21, 2000 (2000-03-21)
1ACX14

14
7
"The King Is Dead"
Monte Young
Craig Hoffman
March 28, 2000 (2000-03-28)
1ACX15

15
8
"I Am Peter, Hear Me Roar"
Monte Young
Chris Sheridan
March 28, 2000 (2000-03-28)
2ACX02

16
9
"If I'm Dyin', I'm Lyin'"
Swinton Scott III
Chris Sheridan
April 4, 2000 (2000-04-04)
1ACX12

17
10
"Running Mates"
John Holmquist
Garrett Donovan & Neil Goldman
April 11, 2000 (2000-04-11)
1ACX09

18
11
"A Picture Is Worth a 1,000 Bucks"
Gavin Dell
Craig Hoffman
April 18, 2000 (2000-04-18)
2ACX07

19
12
"Fifteen Minutes of Shame"
Scott Wood
Steve Callaghan
April 25, 2000 (2000-04-25)
2ACX08

20
13
"Road to Rhode Island"
Dan Povenmire
Gary Janetti
May 30, 2000 (2000-05-30)
2ACX12

21
14
"Let's Go to the Hop"
Glen Hill
Mike Barker & Matt Weitzman
June 6, 2000 (2000-06-06)
2ACX04

22
15
"Dammit Janet"
Bert Ring
Mike Barker & Matt Weitzman
June 13, 2000 (2000-06-13)
2ACX09

23
16
"There's Something About Paulie"
Monte Young
Ricky Blitt
June 27, 2000 (2000-06-27)
1ACX10

24
17
"He's Too Sexy for His Fat"
Glen Hill
Chris Sheridan
June 27, 2000 (2000-06-27)
2ACX10

25
18
"E. Peterbus Unum"
Rob Renzetti
Neil Goldman & Garrett Donovan
July 12, 2000 (2000-07-12)
2ACX13

26
19
"The Story on Page One"
Gavin Dell
Craig Hoffman
July 18, 2000 (2000-07-18)
2ACX14

27
20
"Wasted Talent"
Bert Ring
Story by : Dave Collard & Ken Goin
Teleplay by : Mike Barker & Matt Weitzman
July 25, 2000 (2000-07-25)
2ACX15

28
21
"Fore, Father"
Scott Wood
Bobby Bowman
August 1, 2000 (2000-08-01)
2ACX16

text: Season 3 (2001–03)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code

29
1
"The Thin White Line"
Glen Hill
Steve Callaghan
July 11, 2001 (2001-07-11)
2ACX17

30
2
"Brian Does Hollywood"
Gavin Dell
Gary Janetti
July 18, 2001 (2001-07-18)
2ACX20

31
3
"Mr. Griffin Goes to Washington"
Brian Hogan
Ricky Blitt
July 25, 2001 (2001-07-25)
2ACX11

32
4
"One If by Clam, Two If by Sea"
Dan Povenmire
Jim Bernstein & Michael Shipley
August 1, 2001 (2001-08-01)
2ACX19

33
5
"And the Wiener Is..."
Bert Ring
Mike Barker & Matt Weitzman
August 8, 2001 (2001-08-08)
2ACX22

34
6
"Death Lives"
Rob Renzetti
Mike Henry
August 15, 2001 (2001-08-15)
2ACX21

35
7
"Lethal Weapons"
Brian Hogan
Chris Sheridan
August 22, 2001 (2001-08-22)
2ACX18

36
8
"The Kiss Seen Around the World"
Pete Michels
Mark Hentemann
August 29, 2001 (2001-08-29)
3ACX02

37
9
"Mr. Saturday Knight"
Michael Dante DiMartino
Steve Callaghan
September 5, 2001 (2001-09-05)
3ACX04

38
10
"A Fish Out of Water"
Bert Ring
Alex Borstein & Mike Henry
September 19, 2001 (2001-09-19)
3ACX05

39
11
"Emission Impossible"
Peter Shin
Dave Collard & Ken Goin
November 8, 2001 (2001-11-08)
3ACX01

40
12
"To Love and Die in Dixie"
Dan Povenmire
Steve Callaghan
November 15, 2001 (2001-11-15)
3ACX09

41
13
"Screwed the Pooch"
Pete Michels
Dave Collard & Ken Goin
November 29, 2001 (2001-11-29)
3ACX08

42
14
"Peter Griffin: Husband, Father... Brother?"
Scott Wood
Mike Barker & Matt Weitzman
December 6, 2001 (2001-12-06)
3ACX06

43
15
"Ready, Willing, and Disabled"
Andi Klein
Alex Barnow & Marc Firek
December 20, 2001 (2001-12-20)
3ACX07

44
16
"A Very Special Family Guy Freakin' Christmas"
Brian Hogan
Danny Smith
December 21, 2001 (2001-12-21)
2ACX03

45
17
"Brian Wallows and Peter's Swallows"
Dan Povenmire
Allison Adler
January 17, 2002 (2002-01-17)
3ACX03

46
18
"From Method to Madness"
Bert Ring
Mike Barker & Matt Weitzman
January 24, 2002 (2002-01-24)
3ACX11

47
19
"Stuck Together, Torn Apart"
Michael Dante DiMartino
Mark Hentemann
January 31, 2002 (2002-01-31)
3ACX10

48
20
"Road to Europe"
Dan Povenmire
Daniel Palladino
February 7, 2002 (2002-02-07)
3ACX13

49
21
"Family Guy Viewer Mail #1"
Pete Michels

Scott Wood

Michael Dante DiMartino
Gene Laufenberg

Seth MacFarlane

Michael Shipley & Jim Bernstein
February 14, 2002 (2002-02-14)
3ACX12

50
22
"When You Wish Upon a Weinstein"
Dan Povenmire
Ricky Blitt
November 9, 2003 (2003-11-09) (on Adult Swim)
December 10, 2004 (on Fox)
2ACX05

text: Season 4 (2005–06)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

51
1
"North by North Quahog"
Peter Shin
Seth MacFarlane
May 1, 2005 (2005-05-01)
4ACX01
11.85[32]

52
2
"Fast Times at Buddy Cianci Jr. High"
Pete Michels
Ken Goin
May 8, 2005 (2005-05-08)
4ACX02
9.71[33]

53
3
"Blind Ambition"
Chuck Klein
Steve Callaghan
May 15, 2005 (2005-05-15)
4ACX04
9.21[34]

54
4
"Don't Make Me Over"
Sarah Frost
Gene Laufenberg
June 5, 2005 (2005-06-05)
4ACX03
7.23[35]

55
5
"The Cleveland–Loretta Quagmire"
James Purdum
Mike Henry & Patrick Henry
June 12, 2005 (2005-06-12)
4ACX08
8.35[36]

56
6
"Petarded"
Seth Kearsley
Alec Sulkin & Wellesley Wild
June 19, 2005 (2005-06-19)
4ACX09
7.23[35]

57
7
"Brian the Bachelor"
Dan Povenmire
Mark Hentemann
June 26, 2005 (2005-06-26)
4ACX10
7.29[37]

58
8
"8 Simple Rules for Buying My Teenage Daughter"
Greg Colton
Patrick Meighan
July 10, 2005 (2005-07-10)
4ACX11
6.1[38]

59
9
"Breaking Out Is Hard to Do"
Kurt Dumas
Tom Devanney
July 17, 2005 (2005-07-17)
4ACX12
5.75[39]

60
10
"Model Misbehavior"
Sarah Frost
Steve Callaghan
July 24, 2005 (2005-07-24)
4ACX13
6.73[40]

61
11
"Peter's Got Woods"
Chuck Klein & Zac Moncrief
Danny Smith
September 11, 2005 (2005-09-11)
4ACX14
9.22[41]

62
12
"Perfect Castaway"
James Purdum
John Viener
September 18, 2005 (2005-09-18)
4ACX15
8.68[42]

63
13
"Jungle Love"
Seth Kearsley
Mark Hentemann
September 25, 2005 (2005-09-25)
4ACX16
8.56[43]

64
14
"PTV"
Dan Povenmire
Alec Sulkin & Wellesley Wild
November 6, 2005 (2005-11-06)
4ACX17
7.98[44]

65
15
"Brian Goes Back to College"
Greg Colton
Matt Fleckenstein
November 13, 2005 (2005-11-13)
4ACX18
9.20[45]

66
16
"The Courtship of Stewie's Father"
Kurt Dumas
Kirker Butler
November 20, 2005 (2005-11-20)
4ACX19
9.08[46]

67
17
"The Fat Guy Strangler"
Sarah Frost
Chris Sheridan
November 27, 2005 (2005-11-27)
4ACX20
9.85[47]

68
18
"The Father, the Son, and the Holy Fonz"
James Purdum
Danny Smith
December 18, 2005 (2005-12-18)
4ACX22
8.26[48]

69
19
"Brian Sings and Swings"
Chuck Klein & Zac Moncrief
Michael Rowe
January 8, 2006 (2006-01-08)
4ACX21
8.10[49]

70
20
"Patriot Games"
Cyndi Tang
Mike Henry
January 29, 2006 (2006-01-29)
4ACX25
9.08[50]

71
21
"I Take Thee Quagmire"
Seth Kearsley
Tom Maxwell & Don Woodard and Steve Callaghan
March 12, 2006 (2006-03-12)
4ACX23
8.06[51]

72
22
"Sibling Rivalry"
Dan Povenmire
Cherry Chevapravatdumrong
March 26, 2006 (2006-03-26)
4ACX24
7.95[52]

73
23
"Deep Throats"
Greg Colton
Alex Borstein
April 9, 2006 (2006-04-09)
4ACX26
7.88[53]

74
24
"Peterotica"
Kurt Dumas
Patrick Meighan
April 23, 2006 (2006-04-23)
4ACX27
7.82[54]

75
25
"You May Now Kiss the... Uh... Guy Who Receives"
Dominic Polcino
David A. Goodman
April 30, 2006 (2006-04-30)
4ACX28
7.82[55]

76
26
"Petergeist"
Sarah Frost
Alec Sulkin & Wellesley Wild
May 7, 2006 (2006-05-07)
4ACX29
7.85[56]

77
27
"The Griffin Family History"
Zac Moncrief
John Viener
May 14, 2006 (2006-05-14)
4ACX30
7.87[57]

78
28
"Stewie B. Goode"[a]
Pete Michels
Gary Janetti & Chris Sheridan
May 21, 2006 (2006-05-21)
4ACX05
7.88[58]

79
29
"Bango Was His Name, Oh!"[a]
Pete Michels
Alex Borstein
May 21, 2006 (2006-05-21)
4ACX06
7.88[58]

80
30
"Stu and Stewie's Excellent Adventure"[a]
Pete Michels
Steve Callaghan
May 21, 2006 (2006-05-21)
4ACX07
7.88[58]

text: ^ Jump up to: a b c "Stewie B. Goode", "Bango Was His Name, Oh!" and "Stu and Stewie's Excellent Adventure" make up the direct-to-DVD movie Stewie Griffin: The Untold Story.

tag: ol

text: Season 5 (2006–07)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

81
1
"Stewie Loves Lois"
Mike Kim
Mark Hentemann
September 10, 2006 (2006-09-10)
4ACX32
9.93[59]

82
2
"Mother Tucker"
James Purdum
Tom Devanney
September 17, 2006 (2006-09-17)
4ACX31
9.23[60]

83
3
"Hell Comes to Quahog"
Dan Povenmire
Kirker Butler
September 24, 2006 (2006-09-24)
4ACX33
9.66[61]

84
4
"Saving Private Brian"
Cyndi Tang
Cherry Chevapravatdumrong
November 5, 2006 (2006-11-05)
4ACX34
8.45[62]

85
5
"Whistle While Your Wife Works"
Greg Colton
Steve Callaghan
November 12, 2006 (2006-11-12)
4ACX35
9.04[63]

86
6
"Prick Up Your Ears"
James Purdum
Cherry Chevapravatdumrong
November 19, 2006 (2006-11-19)
5ACX01
9.3[63]

87
7
"Chick Cancer"
Pete Michels
Alec Sulkin & Wellesley Wild
November 26, 2006 (2006-11-26)
5ACX02
9.49[64]

88
8
"Barely Legal"
Zac Moncrief
Kirker Butler
December 17, 2006 (2006-12-17)
5ACX03
8.48[65]

89
9
"Road to Rupert"
Dan Povenmire
Patrick Meighan
January 28, 2007 (2007-01-28)
5ACX04
8.8[66]

90
10
"Peter's Two Dads"
Cyndi Tang
Danny Smith
February 11, 2007 (2007-02-11)
5ACX05
7.97[67]

91
11
"The Tan Aquatic with Steve Zissou"
Julius Wu
Mark Hentemann
February 18, 2007 (2007-02-18)
5ACX06
8.53[68]

92
12
"Airport '07"
John Holmquist
Tom Devanney
March 4, 2007 (2007-03-04)
5ACX08
8.59[69]

93
13
"Bill & Peter's Bogus Journey"
Dominic Polcino
Steve Callaghan
March 11, 2007 (2007-03-11)
5ACX07
8.05[70]

94
14
"No Meals on Wheels"
Greg Colton
Mike Henry
March 25, 2007 (2007-03-25)
5ACX09
7.97[71]

95
15
"Boys Do Cry"
Brian Iles
Cherry Chevapravatdumrong
April 29, 2007 (2007-04-29)
5ACX10
8.13[72]

96
16
"No Chris Left Behind"
Pete Michels
Patrick Meighan
May 6, 2007 (2007-05-06)
5ACX11
7.95[73]

97
17
"It Takes a Village Idiot, and I Married One"
Zac Moncrief
a.bo[a]
May 13, 2007 (2007-05-13)
5ACX12
7.21[74]

98
18
"Meet the Quagmires"
Dan Povenmire & Chris Robertson
Mark Hentemann
May 20, 2007 (2007-05-20)
5ACX13
9.15[75]

text: Jump up ^ "a.bo" is a pseudonym for Alex Borstein.

text: Season 6 (2007–08)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

99
1
"Blue Harvest"
Dominic Polcino
Alec Sulkin
September 23, 2007 (2007-09-23)
5ACX16
5ACX22
10.86[76]

100
2
"Movin' Out (Brian's Song)"
Cyndi Tang
John Viener
September 30, 2007 (2007-09-30)
5ACX14
7.95[77]

101
3
"Believe It or Not, Joe's Walking on Air"
Julius Wu
Andrew Goldberg
October 7, 2007 (2007-10-07)
5ACX15
8.39[77]

Special
TBA
"100th Episode Special"
TBA
Tom Devanney & Alec Sulkin & John Viener & Wellesley Wild
November 4, 2007 (2007-11-04)
6ACX45
10.48[78]

102
4
"Stewie Kills Lois" (Part 1)
John Holmquist
David A. Goodman
November 4, 2007 (2007-11-04)
5ACX17
10.50[78]

103
5
"Lois Kills Stewie" (Part 2)
Greg Colton
Steve Callaghan
November 11, 2007 (2007-11-11)
5ACX18
10.42[79]

104
6
"Padre de Familia"
Pete Michels
Kirker Butler
November 18, 2007 (2007-11-18)
5ACX20
10.53[80]

105
7
"Peter's Daughter"
Zac Moncrief
Chris Sheridan
November 25, 2007 (2007-11-25)
5ACX21
9.60[81]

106
8
"McStroke"
Brian Iles
Wellesley Wild
January 13, 2008 (2008-01-13)
5ACX19
11.50[82]

107
9
"Back to the Woods"
Brian Iles
Tom Devanney
February 17, 2008 (2008-02-17)
6ACX02
7.23[83]

108
10
"Play It Again, Brian"
John Holmquist
Danny Smith
March 2, 2008 (2008-03-02)
6ACX01
7.80[84]

109
11
"The Former Life of Brian"
Pete Michels
Steve Callaghan
April 27, 2008 (2008-04-27)
6ACX04
8.49[85]

110
12
"Long John Peter"
Dominic Polcino
Wellesley Wild
May 4, 2008 (2008-05-04)
6ACX06
7.68[86]

text: Season 7 (2008–09)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

111
1
"Love, Blactually"
Cyndi Tang
Mike Henry
September 28, 2008 (2008-09-28)
6ACX03
9.20[87]

112
2
"I Dream of Jesus"
Mike Kim
Brian Scully
October 5, 2008 (2008-10-05)
6ACX05
8.42[88]

113
3
"Road to Germany"
Greg Colton
Patrick Meighan
October 19, 2008 (2008-10-19)
6ACX08
9.07[89]

114
4
"Baby Not on Board"
Julius Wu
Mark Hentemann
November 2, 2008 (2008-11-02)
6ACX07
9.97[90]

115
5
"The Man with Two Brians"
Dominic Bianchi
John Viener
November 9, 2008 (2008-11-09)
6ACX09
8.60[91]

116
6
"Tales of a Third Grade Nothing"
Jerry Langford
Alex Carter
November 16, 2008 (2008-11-16)
6ACX10
8.52[92]

117
7
"Ocean's Three and a Half"
John Holmquist
Cherry Chevapravatdumrong
February 15, 2009 (2009-02-15)
6ACX11
7.33[93]

118
8
"Family Gay"
Brian Iles
Richard Appel
March 8, 2009 (2009-03-08)
6ACX12
7.18[94]

119
9
"The Juice Is Loose"
Cyndi Tang
Andrew Goldberg
March 15, 2009 (2009-03-15)
6ACX13
7.21[95]

120
10
"Fox-y Lady"
Pete Michels
Matt Fleckenstein
March 22, 2009 (2009-03-22)
6ACX14
7.45[96]

121
11
"Not All Dogs Go to Heaven"
Greg Colton
Danny Smith
March 29, 2009 (2009-03-29)
6ACX17
8.20[97]

122
12
"420"
Julius Wu
Patrick Meighan
April 19, 2009 (2009-04-19)
6ACX16
7.40[98]

123
13
"Stew-Roids"
Jerry Langford
Alec Sulkin
April 26, 2009 (2009-04-26)
6ACX18
6.80[99]

124
14
"We Love You, Conrad"
John Holmquist
Cherry Chevapravatdumrong
May 3, 2009 (2009-05-03)
6ACX19
6.67[100]

125
15
"Three Kings"
Dominic Bianchi
Alec Sulkin
May 10, 2009 (2009-05-10)
6ACX15
6.47[101]

126
16
"Peter's Progress"
Brian Iles
Wellesley Wild
May 17, 2009 (2009-05-17)
6ACX20
7.33[102]

text: Season 8 (2009–10)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

127
1
"Road to the Multiverse"
Greg Colton
Wellesley Wild
September 27, 2009 (2009-09-27)
7ACX06
10.17[103]

128
2
"Family Goy"
James Purdum
Mark Hentemann
October 4, 2009 (2009-10-04)
7ACX01
9.66[104]

129
3
"Spies Reminiscent of Us"
Cyndi Tang
Alec Sulkin
October 11, 2009 (2009-10-11)
7ACX03
8.88[105]

130
4
"Brian's Got a Brand New Bag"
Pete Michels
Tom Devanney
November 8, 2009 (2009-11-08)
7ACX02
7.38[106]

Special
TBA
"Family Guy Presents: Seth & Alex's Almost Live Comedy Show"
Jackson Douglas
Louis J. Horvitz
Aaron Blitzstein
Alex Borstein
Cherry Chevapravatdumrong
Andrew Goldberg
Dave Ihlenfeld
Artie Johann
Seth MacFarlane
Patrick Meighan
Danny Smith
Alec Sulkin
John Viener
Wellesley Wild
November 8, 2009 (2009-11-08)
1ARX01
6.63[107]

131
5
"Hannah Banana"
John Holmquist
Cherry Chevapravatdumrong
November 8, 2009 (2009-11-08)
7ACX05
7.73[108]

132
6
"Quagmire's Baby"
Jerry Langford
Patrick Meighan
November 15, 2009 (2009-11-15)
7ACX04
8.28[109]

133
7
"Jerome Is the New Black"
Brian Iles
John Viener
November 22, 2009 (2009-11-22)
7ACX08
7.38[110]

134
8
"Dog Gone"
Julius Wu
Steve Callaghan
November 29, 2009 (2009-11-29)
7ACX07
8.48[111]

135
9
"Business Guy"
Pete Michels
Andrew Goldberg & Alex Carter
December 13, 2009 (2009-12-13)
7ACX11
7.67[112]

136
10
"Big Man on Hippocampus"
Dominic Bianchi
Brian Scully
January 3, 2010 (2010-01-03)
7ACX09
8.10[113]

137
11
"Dial Meg for Murder"
Cyndi Tang
Alex Carter & Andrew Goldberg
January 31, 2010 (2010-01-31)
7ACX12
6.21[114]

138
12
"Extra Large Medium"
John Holmquist
Steve Callaghan
February 14, 2010 (2010-02-14)
7ACX14
6.42[115]

139
13
"Go, Stewie, Go!"
Greg Colton
Gary Janetti
March 14, 2010 (2010-03-14)
7ACX15
6.72[116]

140
14
"Peter-assment"
Julius Wu
Chris Sheridan
March 21, 2010 (2010-03-21)
7ACX16
6.65[117]

141
15
"Brian Griffin's House of Payne"
Jerry Langford
Spencer Porter
March 28, 2010 (2010-03-28)
7ACX13
7.27[118]

142
16
"April in Quahog"
Joseph Lee
John Viener
April 11, 2010 (2010-04-11)
7ACX18
6.93[119]

143
17
"Brian & Stewie"
Dominic Bianchi
Gary Janetti
May 2, 2010 (2010-05-02)
7ACX20
7.68[120]

144
18
"Quagmire's Dad"
Pete Michels
Tom Devanney
May 9, 2010 (2010-05-09)
7ACX19
7.22[121]

145
19
"The Splendid Source"
Brian Iles
Based on a short story by : Richard Matheson
Written by : Mark Hentemann
May 16, 2010 (2010-05-16)
7ACX17
7.59[122]

146
20
"Something, Something, Something, Dark Side"
Dominic Polcino
Kirker Butler
May 23, 2010 (2010-05-23)
6ACX21
6ACX22
6.13[123]

147
21
"Partial Terms of Endearment"
Joseph Lee
Danny Smith
June 20, 2010 (2010-06-20) (on BBC Three)
7ACX10
N/A

text: Season 9 (2010–11)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

148
1
"And Then There Were Fewer"
Dominic Polcino
Cherry Chevapravatdumrong
September 26, 2010 (2010-09-26)
8ACX01
8ACX02
9.41[124]

149
2
"Excellence in Broadcasting"
John Holmquist
Patrick Meighan
October 3, 2010 (2010-10-03)
8ACX03
7.94[125]

150
3
"Welcome Back, Carter"
Cyndi Tang
Wellesley Wild
October 10, 2010 (2010-10-10)
8ACX04
7.02[126]

151
4
"Halloween on Spooner Street"
Jerry Langford
Andrew Goldberg
November 7, 2010 (2010-11-07)
8ACX06
7.97[127]

152
5
"Baby, You Knock Me Out"
Julius Wu
Alex Carter
November 14, 2010 (2010-11-14)
8ACX05
7.00[128]

153
6
"Brian Writes a Bestseller"
Joseph Lee
Gary Janetti
November 21, 2010 (2010-11-21)
8ACX07
6.59[129]

154
7
"Road to the North Pole"
Greg Colton
Chris Sheridan & Danny Smith
December 12, 2010 (2010-12-12)
8ACX08
8ACX09
8.03[130]

155
8
"New Kidney in Town"
Pete Michels
Matt Harrigan & Dave Willis
January 9, 2011 (2011-01-09)
8ACX10
9.29[131]

156
9
"And I'm Joyce Kinney"
Dominic Bianchi
Alec Sulkin
January 16, 2011 (2011-01-16)
8ACX12
7.08[132]

157
10
"Friends of Peter G."
John Holmquist
Brian Scully
February 13, 2011 (2011-02-13)
8ACX13
5.99[133]

158
11
"German Guy"
Cyndi Tang
Patrick Meighan
February 20, 2011 (2011-02-20)
8ACX14
6.56[134]

159
12
"The Hand That Rocks the Wheelchair"
Brian Iles
Tom Devanney
March 6, 2011 (2011-03-06)
8ACX11
6.32[135]

160
13
"Trading Places"
Joseph Lee
Steve Callaghan
March 20, 2011 (2011-03-20)
8ACX17
6.55[136]

161
14
"Tiegs for Two"
Jerry Langford
John Viener
April 10, 2011 (2011-04-10)
8ACX16
6.61[137]

162
15
"Brothers & Sisters"
Julius Wu
Alex Carter
April 17, 2011 (2011-04-17)
8ACX15
6.04[138]

163
16
"The Big Bang Theory"
Dominic Polcino
David A. Goodman
May 8, 2011 (2011-05-08)
8ACX18
6.52[139]

164
17
"Foreign Affairs"
Pete Michels
Anthony Blasucci & Mike Desilets
May 15, 2011 (2011-05-15)
8ACX19
6.55[140]

165
18
"It's a Trap!"
Peter Shin
Cherry Chevapravatdumrong & David A. Goodman
May 22, 2011 (2011-05-22)
7ACX21
7ACX22
5.83[141]

text: Season 10 (2011–12)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

166
1
"Lottery Fever"
Greg Colton
Andrew Goldberg
September 25, 2011 (2011-09-25)
9ACX01
7.69[142]

167
2
"Seahorse Seashell Party"
Brian Iles
Wellesley Wild
October 2, 2011 (2011-10-02)
8ACX20
6.99[143]

168
3
"Screams of Silence: The Story of Brenda Q"
Dominic Bianchi
Alec Sulkin
October 30, 2011 (2011-10-30)
8ACX21
5.96[144]

169
4
"Stewie Goes for a Drive"
Julius Wu
Gary Janetti
November 6, 2011 (2011-11-06)
9ACX02
5.82[145]

170
5
"Back to the Pilot"
Dominic Bianchi
Mark Hentemann
November 13, 2011 (2011-11-13)
9ACX08
6.01[146]

171
6
"Thanksgiving"
Jerry Langford
Patrick Meighan
November 20, 2011 (2011-11-20)
9ACX04
6.02[147]

172
7
"Amish Guy"
John Holmquist
Mark Hentemann
November 27, 2011 (2011-11-27)
8ACX22
5.50[148]

173
8
"Cool Hand Peter"
Brian Iles
Artie Johann & Shawn Ries
December 4, 2011 (2011-12-04)
9ACX05
7.14[149]

174
9
"Grumpy Old Man"
John Holmquist
Dave Ihlenfeld & David Wright
December 11, 2011 (2011-12-11)
9ACX07
6.10[150]

175
10
"Meg and Quagmire"
Joseph Lee
Tom Devanney
January 8, 2012 (2012-01-08)
9ACX03
6.23[151]

176
11
"The Blind Side"
Bob Bowen
Cherry Chevapravatdumrong
January 15, 2012 (2012-01-15)
9ACX06
8.31[152]

177
12
"Livin' on a Prayer"
Pete Michels
Danny Smith
January 29, 2012 (2012-01-29)
9ACX09
5.92[153]

178
13
"Tom Tucker: The Man and His Dream"
Greg Colton
Alex Carter
February 12, 2012 (2012-02-12)
9ACX10
5.03[154]

179
14
"Be Careful What You Fish For"
Julius Wu
Steve Callaghan
February 19, 2012 (2012-02-19)
9ACX11
5.39[155]

180
15
"Burning Down the Bayit"
Jerry Langford
Chris Sheridan
March 4, 2012 (2012-03-04)
9ACX13
5.33[156]

181
16
"Killer Queen"
Joseph Lee
Spencer Porter
March 11, 2012 (2012-03-11)
9ACX12
5.74[157]

182
17
"Forget-Me-Not"
Brian Iles
David A. Goodman
March 18, 2012 (2012-03-18)
9ACX14
5.61[158]

183
18
"You Can't Do That on Television, Peter"
Bob Bowen
Julius Sharpe
April 1, 2012 (2012-04-01)
9ACX15
5.05[159]

184
19
"Mr. and Mrs. Stewie"
Joe Vaux
Gary Janetti
April 29, 2012 (2012-04-29)
9ACX17
5.63[160]

185
20
"Leggo My Meg-O"
John Holmquist
Brian Scully
May 6, 2012 (2012-05-06)
9ACX16
5.64[161]

186
21
"Tea Peter"
Pete Michels
Patrick Meighan
May 13, 2012 (2012-05-13)
9ACX18
4.94[162]

187
22
"Family Guy Viewer Mail #2"
Greg Colton
Tom Devanney & Alec Sulkin & Deepak Sethi
May 20, 2012 (2012-05-20)
9ACX19
5.35[163]

188
23
"Internal Affairs"
Julius Wu
Wellesley Wild
May 20, 2012 (2012-05-20)
9ACX20
5.35[163]

text: Season 11 (2012–13)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

189
1
"Into Fat Air"
Joseph Lee
Alec Sulkin
September 30, 2012 (2012-09-30)
9ACX21
6.55[164]

190
2
"Ratings Guy"
James Purdum
Dave Ihlenfeld & David Wright
October 7, 2012 (2012-10-07)
AACX01
6.70[165]

191
3
"The Old Man and the Big 'C'"
Brian Iles
Mike Desilets & Anthony Blasucci
November 4, 2012 (2012-11-04)
9ACX22
5.11[166]

192
4
"Yug Ylimaf"
John Holmquist
Mark Hentemann
November 11, 2012 (2012-11-11)
AACX04
5.57[167]

Special
TBA
"200 Episodes Later"
Brad Lachman
Michael O'Rourke
November 11, 2012 (2012-11-11)
AACX45
5.06[167]

193
5
"Joe's Revenge"
Bob Bowen
Julius Sharpe
November 18, 2012 (2012-11-18)
AACX03
5.14[168]

194
6
"Lois Comes Out of Her Shell"
Joe Vaux
Danny Smith
November 25, 2012 (2012-11-25)
AACX05
5.77[169]

195
7
"Friends Without Benefits"
Jerry Langford
Cherry Chevapravatdumrong
December 9, 2012 (2012-12-09)
AACX02
5.64[170]

196
8
"Jesus, Mary and Joseph!"
Julius Wu
Tom Devanney
December 23, 2012 (2012-12-23)
AACX07
5.49[171]

197
9
"Space Cadet"
Pete Michels
Alex Carter
January 6, 2013 (2013-01-06)
AACX06
7.21[172]

198
10
"Brian's Play"
Joseph Lee
Gary Janetti
January 13, 2013 (2013-01-13)
AACX08
6.01[173]

199
11
"The Giggity Wife"
Brian Iles
Andrew Goldberg
January 27, 2013 (2013-01-27)
AACX09
5.63[174]

200
12
"Valentine's Day in Quahog"
Bob Bowen
Daniel Palladino
February 10, 2013 (2013-02-10)
AACX11
4.71[175]

201
13
"Chris Cross"
Jerry Langford
Anthony Blasucci & Mike Desilets
February 17, 2013 (2013-02-17)
AACX10
4.87[176]

202
14
"Call Girl"
John Holmquist
Wellesley Wild
March 10, 2013 (2013-03-10)
AACX12
5.27[177]

203
15
"Turban Cowboy"
Joe Vaux
Artie Johann & Shawn Ries
March 17, 2013 (2013-03-17)
AACX13
4.92[178]

204
16
"12 and a Half Angry Men"
Pete Michels
Ted Jessup
March 24, 2013 (2013-03-24)
AACX14
5.16[179]

205
17
"Bigfat"
Julius Wu
Brian Scully
April 14, 2013 (2013-04-14)
AACX15
5.02[180]

206
18
"Total Recall"
Joseph Lee
Kristin Long
April 28, 2013 (2013-04-28)
AACX16
4.89[181]

207
19
"Save the Clam"
Brian Iles
Chris Sheridan
May 5, 2013 (2013-05-05)
AACX18
4.79[182]

208
20
"Farmer Guy"
Mike Kim
Patrick Meighan
May 12, 2013 (2013-05-12)
AACX19
4.82[183]

209
21
"Roads to Vegas"
Greg Colton
Steve Callaghan
May 19, 2013 (2013-05-19)
AACX20
5.28[184]

210
22
"No Country Club for Old Men"
Jerry Langford
Teresa Hsiao
May 19, 2013 (2013-05-19)
AACX21
5.16[184]

text: Season 12 (2013–14)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

211
1
"Finders Keepers"
John Holmquist
Mike Desilets & Anthony Blasucci
September 29, 2013 (2013-09-29)
BACX01
5.23[185]

212
2
"Vestigial Peter"
Julius Wu
Brian Scully
October 6, 2013 (2013-10-06)
BACX02
5.20[186]

213
3
"Quagmire's Quagmire"
Pete Michels
Cherry Chevapravatdumrong
November 3, 2013 (2013-11-03)
BACX03
4.87[187]

214
4
"A Fistful of Meg"
Joe Vaux
Dominic Bianchi & Joe Vaux
November 10, 2013 (2013-11-10)
AACX22
4.18[188]

215
5
"Boopa-dee Bappa-dee"
Mike Kim
Wellesley Wild
November 17, 2013 (2013-11-17)
BACX04
4.46[189]

216
6
"Life of Brian"
Joseph Lee
Alex Carter
November 24, 2013 (2013-11-24)
BACX05
4.58[190]

217
7
"Into Harmony's Way"
Brian Iles
Julius Sharpe
December 8, 2013 (2013-12-08)
BACX06
5.36[191]

218
8
"Christmas Guy"
Greg Colton
Patrick Meighan
December 15, 2013 (2013-12-15)
BACX07
6.37[192]

219
9
"Peter Problems"
Bob Bowen
Teresa Hsiao
January 5, 2014 (2014-01-05)
BACX08
5.76[193]

220
10
"Grimm Job"
Joe Vaux
Alec Sulkin
January 12, 2014 (2014-01-12)
BACX09
5.22[194]

221
11
"Brian's a Bad Father"
Jerry Langford
Chris Sheridan
January 26, 2014 (2014-01-26)
BACX10
4.11[195]

222
12
"Mom's the Word"
John Holmquist
Ted Jessup
March 9, 2014 (2014-03-09)
BACX11
4.56[196]

223
13
"3 Acts of God"
Bob Bowen
Alec Sulkin
March 16, 2014 (2014-03-16)
AACX17
4.62[197]

224
14
"Fresh Heir"
Mike Kim
Steve Callaghan
March 23, 2014 (2014-03-23)
BACX13
4.38[198]

225
15
"Secondhand Spoke"
Julius Wu
Dave Ihlenfeld & David Wright
March 30, 2014 (2014-03-30)
BACX12
4.17[199]

226
16
"Herpe the Love Sore"
Greg Colton
Andrew Goldberg
April 6, 2014 (2014-04-06)
BACX16
4.77[200]

227
17
"The Most Interesting Man in the World"
Joseph Lee
Tom Devanney
April 13, 2014 (2014-04-13)
BACX14
4.39[201]

228
18
"Baby Got Black"
Brian Iles
Kevin Biggins & Travis Bowe
April 27, 2014 (2014-04-27)
BACX15
4.02[202]

229
19
"Meg Stinks!"
Bob Bowen
Danny Smith
May 4, 2014 (2014-05-04)
BACX17
4.40[203]

230
20
"He's Bla-ack!"
Steve Robertson
Julius Sharpe
May 11, 2014 (2014-05-11)
BACX19
4.16[204]

231
21
"Chap Stewie"
Joe Vaux
Artie Johann & Shawn Ries
May 18, 2014 (2014-05-18)
BACX18
3.88[205]

text: Season 13 (2014–15)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

232
1
"The Simpsons Guy"
Peter Shin
Patrick Meighan
September 28, 2014 (2014-09-28)
BACX22
BACX23
8.45[206]

233
2
"The Book of Joe"
Mike Kim
Mike Desilets
October 5, 2014 (2014-10-05)
CACX01
3.63[207]

234
3
"Baking Bad"
Jerry Langford
Mark Hentemann
October 19, 2014 (2014-10-19)
BACX20
4.74[208]

235
4
"Brian the Closer"
John Holmquist
Steve Marmel
November 9, 2014 (2014-11-09)
BACX21
3.63[209]

236
5
"Turkey Guys"
Julius Wu
Cherry Chevapravatdumrong
November 16, 2014 (2014-11-16)
CACX02
4.46[210]

237
6
"The 2000-Year-Old Virgin"
Joseph Lee
Ted Jessup
December 7, 2014 (2014-12-07)
CACX03
4.44[211]

238
7
"Stewie, Chris, & Brian's Excellent Adventure"
Joe Vaux
Alex Carter
January 4, 2015 (2015-01-04)
CACX04
5.53[212]

239
8
"Our Idiot Brian"
John Holmquist
Aaron Lee
January 11, 2015 (2015-01-11)
CACX05
4.12[213]

240
9
"This Little Piggy"
Brian Iles
Kristin Long
January 25, 2015 (2015-01-25)
CACX06
3.19[214]

241
10
"Quagmire's Mom"
Greg Colton
Tom Devanney
February 8, 2015 (2015-02-08)
CACX07
2.81[215]

242
11
"Encyclopedia Griffin"
Jerry Langford
Lew Morton
February 15, 2015 (2015-02-15)
CACX08
2.51[216]

243
12
"Stewie Is Enceinte"
Steve Robertson
Gary Janetti
March 8, 2015 (2015-03-08)
CACX09
3.98[217]

244
13
"Dr. C and the Women"
Mike Kim
Travis Bowe
March 15, 2015 (2015-03-15)
CACX10
3.45[218]

245
14
"#JOLO"
Julius Wu
Artie Johann & Shawn Ries
April 12, 2015 (2015-04-12)
CACX11
3.11[219]

246
15
"Once Bitten"
Joseph Lee
Anthony Blasucci
April 19, 2015 (2015-04-19)
CACX12
3.30[220]

247
16
"Roasted Guy"
Joe Vaux
Andrew Goldberg
April 26, 2015 (2015-04-26)
CACX13
3.17[221]

248
17
"Fighting Irish"
Brian Iles
Jaydi Samuels
May 3, 2015 (2015-05-03)
CACX15
3.68[222]

249
18
"Take My Wife"
John Holmquist
Kevin Biggins
May 17, 2015 (2015-05-17)
CACX14
2.85[223]

text: Season 14 (2015–16)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

250
1
"Pilling Them Softly"
Jerry Langford
Hayes Davenport
September 27, 2015 (2015-09-27)
CACX17
2.87[224]

251
2
"Papa Has a Rollin' Son"
Steve Robertson
Danny Smith
October 4, 2015 (2015-10-04)
CACX18
3.56[225]

252
3
"Guy, Robot"
Mike Kim
Chris Regan
October 11, 2015 (2015-10-11)
DACX02
2.79[226]

253
4
"Peternormal Activity"
Greg Colton
Chris Sheridan
October 25, 2015 (2015-10-25)
CACX16
3.85[227]

254
5
"Peter, Chris, & Brian"
Joe Vaux
Patrick Meighan
November 8, 2015 (2015-11-08)
DACX03
2.58[228]

255
6
"Peter's Sister"
John Holmquist
Tom Devanney
November 15, 2015 (2015-11-15)
DACX04
2.91[229]

256
7
"Hot Pocket-Dial"
Steve Robertson
Aaron Lee
November 22, 2015 (2015-11-22)
DACX06
3.37[230]

257
8
"Brokeback Swanson"
Julius Wu
Ted Jessup
December 6, 2015 (2015-12-06)
DACX07
3.63[231]

258
9
"A Shot in the Dark"
Brian Iles
Mike Desilets
December 13, 2015 (2015-12-13)
DACX05
3.74[232]

259
10
"Candy, Quahog Marshmallow"
Joseph Lee
Cherry Chevapravatdumrong
January 3, 2016 (2016-01-03)
DACX01
3.26[233]

260
11
"The Peanut Butter Kid"
Greg Colton
Artie Johann
January 10, 2016 (2016-01-10)
DACX08
3.92[234]

261
12
"Scammed Yankees"
Jerry Langford
Ray James
January 17, 2016 (2016-01-17)
DACX09
3.40[235]

262
13
"An App a Day"
Mike Kim
Anthony Blasucci
February 14, 2016 (2016-02-14)
DACX12
2.57[236]

263
14
"Underage Peter"
Joseph Lee
Shawn Ries
February 21, 2016 (2016-02-21)
DACX13
2.72[237]

264
15
"A Lot Going on Upstairs"
Joe Vaux
Steve Callaghan
March 6, 2016 (2016-03-06)
DACX11
2.74[238]

265
16
"The Heartbreak Dog"
Brian Iles
Lew Morton
March 13, 2016 (2016-03-13)
DACX14
2.98[239]

266
17
"Take a Letter"
John Holmquist
Kevin Biggins
April 17, 2016 (2016-04-17)
DACX15
2.93[240]

267
18
"The New Adventures of Old Tom"
Steve Robertson
Travis Bowe
May 8, 2016 (2016-05-08)
DACX16
2.76[241]

268
19
"Run, Chris, Run"
Julius Wu
Damien Fahey
May 15, 2016 (2016-05-15)
DACX17
2.65[242]

269
20
"Road to India"
Greg Colton
Danny Smith
May 22, 2016 (2016-05-22)
DACX18
2.59[243]

text: Season 15 (2016–17)[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

270
1
"The Boys in the Band"
Joseph Lee
Chris Regan
September 25, 2016 (2016-09-25)
EACX01
2.80[244]

271
2
"Bookie of the Year"
Jerry Langford
Daniel Peck
October 2, 2016 (2016-10-02)
DACX10
3.47[245]

272
3
"American Gigg-olo"
Mike Kim
Chris Sheridan
October 16, 2016 (2016-10-16)
DACX19
3.68[246]

273
4
"Inside Family Guy"
Joe Vaux
Andrew Goldberg
October 23, 2016 (2016-10-23)
DACX20
2.49[247]

274
5
"Chris Has Got a Date, Date, Date, Date, Date"
Brian Iles
Artie Johann
November 6, 2016 (2016-11-06)
EACX02
2.60[248]

275
6
"Hot Shots"
John Holmquist
David A. Goodman
November 13, 2016 (2016-11-13)
EACX03
3.58[249]

276
7
"High School English"
Steve Robertson
Ted Jessup
November 20, 2016 (2016-11-20)
EACX04
2.74[250]

277
8
"Carter and Tricia"
Mike Kim
Patrick Meighan
December 4, 2016 (2016-12-04)
EACX05
3.45[251]

278
9
"How the Griffin Stole Christmas"
Julius Wu
Aaron Lee
December 11, 2016 (2016-12-11)
EACX06
3.05[252]

279
10
"Passenger Fatty-Seven"
Greg Colton
Alex Carter
January 8, 2017 (2017-01-08)
EACX07
4.00[253]

280
11
"Gronkowsbees"
Jerry Langford
Cherry Chevapravatdumrong
January 15, 2017 (2017-01-15)
EACX08
3.55[254]

281
12
"Peter's Def Jam"
Joe Vaux
Anthony Blasucci
February 12, 2017 (2017-02-12)
EACX09
1.86[255]

282
13
"The Finer Strings"
Joseph Lee
Shawn Ries
February 19, 2017 (2017-02-19)
EACX10
2.26[256]

283
14
"The Dating Game"
Brian Iles
Tom Devanney
March 5, 2017 (2017-03-05)
EACX11
2.48[257]

284
15
"Cop and a Half-wit"
John Holmquist
Ray James
March 12, 2017 (2017-03-12)
EACX12
2.51[258]

285
16
"Saturated Fat Guy"
Steve Robertson
Damien Fahey
March 19, 2017 (2017-03-19)
EACX13
2.34[259]

286
17
"Peter's Lost Youth"
Julius Wu
Danny Smith
March 26, 2017 (2017-03-26)
EACX14
2.17[260]

287
18
"The Peter Principal"
Greg Colton
Steve Callaghan
April 30, 2017 (2017-04-30)
EACX16
2.42[261]

288
19
"Dearly Deported"
Jerry Langford
Mike Desilets
May 21, 2017 (2017-05-21)
EACX17
2.14[262]

289
20
"A House Full of Peters"
Joseph Lee
Chris Sheridan
May 21, 2017 (2017-05-21)
EACX19
2.14[262]

text: Season 16[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

290
1
"Emmy-Winning Episode"[263]
TBA
TBA
October 1, 2017 (2017-10-01)[264]
FACX06
TBD

291
2
"Foxx in the Men House"[265]
TBA
TBA
October 8, 2017 (2017-10-08)
EACX20
TBD

text: Unscheduled episodes[edit]

text:
Production code
Title
Reference

EACX18
"Three Directors"
[266]

FACX01
"Dog Bites Bear"
[267]

FACX02
"Nanny Goats"
[268]

FACX03
"The D in Apartment 23"
[269]

FACX04
"Petey IV"
[270]

FACX07
"Don't Be a Dickens at Christmas"
[271]

FACX10
"Send in Stewie, Please"
[272]

FACX15
"HTTPete"
[273]

 ?ACX??
"Doc Brown"
[274]

 ?ACX??
"Follow the Money"
[275]

 ?ACX??
"Crimes and Meg's Demeanor"
[276]

 ?ACX??
"V is for Mystery"
[277]

 ?ACX??
"Brian Dates a Bitch"
[278]

 ?ACX??
"Veteran Guy"
[279]

 ?ACX??
"Family Guy Through the Years"
[280]

 ?ACX??
"The Woof of Wall Street"
[281]

text: Specials[edit]

text:
Title
Directed by
Written by
Original air date
Ratings/
Share

"100th Episode Special"
TBA
Tom Devanney & Alec Sulkin & John Viener & Wellesley Wild
November 4, 2007 (2007-11-04)
10.48[78]

Seth MacFarlane hosts a special looking back at the most memorable episodes from the past 100 episodes of Family Guy.

"Family Guy Presents: Seth & Alex's Almost Live Comedy Show"
Jackson Douglas & Louis J. Horvitz
Aaron Blitzstein & Alex Borstein & Cherry Chevapravatdumrong & Andrew Goldberg & Dave Ihlenfeld & Artie Johann & Seth MacFarlane & Patrick Meighan & Danny Smith & Alec Sulkin & John Viener & Wellesley Wild
November 8, 2009 (2009-11-08)
6.63[282]

Seth MacFarlane and Alex Borstein host a half-hour variety special.

"200 Episodes Later"
Brad Lachman
Michael O'Rourke
November 11, 2012 (2012-11-11)
5.06[167]

Fans get a look behind the scenes at the most outrageous moments on Family Guy.

text: Home media[edit]

text:
Season
Episodes
DVD volume/season/special
(Region 1)
DVD season/special
(Region 2/4)
DVD release date

Region 1
Region 2
Region 4
Discs

1
7
1
1
April 15, 2003[283]
November 12, 2001[284]
October 20, 2003[285]
4

2
21
2
January 27, 2003[286]
August 2, 2004[287]

3
22
2
3
September 9, 2003[288]
July 21, 2003[289]
May 2, 2005[290]
3

4
30
3
4
November 29, 2005[291]
April 24, 2006[292]
May 29, 2006[293]
3

4
5
November 14, 2006[294]
October 30, 2006[295]
November 1, 2006[296]
3

Stewie Griffin:
The Untold Story
Stewie Griffin:
The Untold Story
September 27, 2005[297]
October 24, 2005[298]
January 25, 2006[299]
1

5
18
5
6
September 18, 2007[300]
October 15, 2007[301]
October 17, 2007[302]
3

6
12
6
7
October 21, 2008[303]
November 10, 2008[304]
December 10, 2008[305]
3

"Blue Harvest"3 4
"Blue Harvest"3 4
January 15, 2008[306]
January 21, 2008[307]
February 5, 2008[308]
1

7
16
7
8
June 16, 2009[309]
November 2, 2009[310]
September 29, 2009[311]
3

8
21
8
9
June 15, 2010[312]
November 1, 2010[313]
August 17, 2010[314]
3

"Something, Something,
Something, Dark Side"1 4
"Something, Something,
Something, Dark Side"1 4
December 22, 2009[315]
December 26, 2009[316]
December 23, 2009[317]
1

9
18
9
10
December 13, 2011[318]
May 9, 2011[319]
June 15, 2011[320]
3

10
11
September 25, 2012[321]
November 7, 2011[322]
February 29, 2012[323]
3

"It's a Trap!"2 4
"It's a Trap!"2 4
December 21, 2010[324]
December 27, 2010[325]
December 22, 2010[326]
1

10
23
11
12
September 24, 2013[327]
November 4, 2013[328]
October 9, 2013 (2013-10-09)[329]
3

11
22
12
13
December 17, 2013[330]
June 9, 2014[331]
May 14, 2014[332]
3

12
21
12[a]
14
December 9, 2014[333]
November 10, 2014[334]
December 10, 2014[335]
3

13
18
13
15
December 8, 2015[336]
November 16, 2015[337]
December 2, 2015[338]
3

14
20
14
16
December 6, 2016[339]
November 7, 2016[340]
November 30, 2016[341]
3

text: Jump up ^ From Season 12 onwards, Region 1 releases were listed as seasons.


document_title: Standard deviation

question_text: what does the little u mean in statistics

question_tokens: what does the little u mean in statistics

text: Standard deviation

text: Basic examples[edit]

text: Sample standard deviation of metabolic rate of Northern Fulmars[edit]

text: Logan [5] gives the following example. Furness and Bryant [6] measured the resting metabolic rate for 8 male and 6 female breeding Northern fulmars. The table shows the furness data set.

text: The graph shows the metabolic rate for males and females. By visual inspection, it appears that the variability of the metabolic rate is greater for males than for females.

text: The sample standard deviation of the metabolic rate for the female fulmars is calculated as follows. The formula for the sample standard deviation is

text:
where

{

x

1

,

x

2

,

…
,

x

N

}

{\displaystyle \scriptstyle \{x_{1},\,x_{2},\,\ldots ,\,x_{N}\}}

 are the observed values of the sample items,

x
¯

{\displaystyle \scriptstyle {\overline {x}}}

 is the mean value of these observations, and N is the number of observations in the sample.

text: In the sample standard deviation formula, for this example, the numerator is the sum of the squared deviation of each individual animal's metabolic rate from the mean metabolic rate. The table below shows the calculation of this sum of squared deviations for the female fulmars. For females, the sum of squared deviations is 886047.09, as shown in the table.

text: The denominator in the sample standard deviation formula is N – 1, where N is the number of animals. In this example, there are N = 6 females, so the denominator is 6 – 1 = 5. The sample standard deviation for the female fulmars is therefore

text: For the male fulmars, a similar calculation gives a sample standard deviation of 894.37, approximately twice as large as the standard deviation for the females. The graph shows the metabolic rate data, the means (red dots), and the standard deviations (red lines) for females and males.

text: Use of the sample standard deviation implies that these 14 fulmars are a sample from a larger population of fulmars. If these 14 fulmars comprised the entire population (perhaps the last 14 surviving fulmars), then instead of the sample standard deviation, the calculation would use the population standard deviation. In the population standard deviation formula, the denominator is N instead of N-1. It is rare that measurements can be taken for an entire population, so, by default, statistical software packages calculate the sample standard deviation. Similarly, journal articles report the sample standard deviation unless otherwise specified.

text: Population standard deviation of grades of eight students[edit]

text: Suppose that the entire population of interest was eight students in a particular class. For a finite set of numbers, the population standard deviation is found by taking the square root of the average of the squared deviations of the values from their average value. The marks of a class of eight students (that is, a statistical population) are the following eight values:

text: These eight data points have the mean (average) of 5:

text: First, calculate the deviations of each data point from the mean, and square the result of each:

text: The variance is the mean of these values:

text: and the population standard deviation is equal to the square root of the variance:

text: This formula is valid only if the eight values with which we began form the complete population. If the values instead were a random sample drawn from some large parent population (for example, they were 8 marks randomly and independently chosen from a class of 2 million), then one often divides by 7 (which is n − 1) instead of 8 (which is n) in the denominator of the last formula. In that case the result of the original formula would be called the sample standard deviation. Dividing by n − 1 rather than by n gives an unbiased estimate of the variance of the larger parent population. This is known as Bessel's correction.[7]

text: Standard deviation of average height for adult men[edit]

text: If the population of interest is approximately normally distributed, the standard deviation provides information on the proportion of observations above or below certain values. For example, the average height for adult men in the United States is about 70 inches (177.8 cm), with a standard deviation of around 3 inches (7.62 cm). This means that most men (about 68%, assuming a normal distribution) have a height within 3 inches (7.62 cm) of the mean (67–73 inches (170.18–185.42 cm)) – one standard deviation – and almost all men (about 95%) have a height within 6 inches (15.24 cm) of the mean (64–76 inches (162.56–193.04 cm)) – two standard deviations. If the standard deviation were zero, then all men would be exactly 70 inches (177.8 cm) tall. If the standard deviation were 20 inches (50.8 cm), then men would have much more variable heights, with a typical range of about 50–90 inches (127–228.6 cm). Three standard deviations account for 99.7% of the sample population being studied, assuming the distribution is normal (bell-shaped). (See the 68-95-99.7 rule, or the empirical rule, for more information.)

text: Definition of population values[edit]

text: Let X be a random variable with mean value μ:

text: Here the operator E denotes the average or expected value of X. Then the standard deviation of X is the quantity

text: (derived using the properties of expected value).

text: In other words, the standard deviation σ (sigma) is the square root of the variance of X; i.e., it is the square root of the average value of (X − μ)2.

text: The standard deviation of a (univariate) probability distribution is the same as that of a random variable having that distribution. Not all random variables have a standard deviation, since these expected values need not exist. For example, the standard deviation of a random variable that follows a Cauchy distribution is undefined because its expected value μ is undefined.

text: Discrete random variable[edit]

text: In the case where X takes random values from a finite data set x1, x2, ..., xN, with each value having the same probability, the standard deviation is

text: or, using summation notation,

text: If, instead of having equal probabilities, the values have different probabilities, let x1 have probability p1, x2 have probability p2, ..., xN have probability pN. In this case, the standard deviation will be

text: Continuous random variable[edit]

text: The standard deviation of a continuous real-valued random variable X with probability density function p(x) is

text: and where the integrals are definite integrals taken for x ranging over the set of possible values of the random variable X.

text: In the case of a parametric family of distributions, the standard deviation can be expressed in terms of the parameters. For example, in the case of the log-normal distribution with parameters μ and σ2, the standard deviation is [(exp(σ2) − 1)exp(2μ + σ2)]1/2.

text: Estimation[edit]

text: One can find the standard deviation of an entire population in cases (such as standardized testing) where every member of a population is sampled. In cases where that cannot be done, the standard deviation σ is estimated by examining a random sample taken from the population and computing a statistic of the sample, which is used as an estimate of the population standard deviation. Such a statistic is called an estimator, and the estimator (or the value of the estimator, namely the estimate) is called a sample standard deviation, and is denoted by s (possibly with modifiers). However, unlike in the case of estimating the population mean, for which the sample mean is a simple estimator with many desirable properties (unbiased, efficient, maximum likelihood), there is no single estimator for the standard deviation with all these properties, and unbiased estimation of standard deviation is a very technically involved problem. Most often, the standard deviation is estimated using the corrected sample standard deviation (using N − 1), defined below, and this is often referred to as the "sample standard deviation", without qualifiers. However, other estimators are better in other respects: the uncorrected estimator (using N) yields lower mean squared error, while using N − 1.5 (for the normal distribution) almost completely eliminates bias.

text: Uncorrected sample standard deviation[edit]

text: The formula for the population standard deviation (of a finite population) can be applied to the sample, using the size of the sample as the size of the population (though the actual population size from which the sample is drawn may be much larger). This estimator, denoted by sN, is known as the uncorrected sample standard deviation, or sometimes the standard deviation of the sample (considered as the entire population), and is defined as follows:[citation needed]

text:
where

{

x

1

,

x

2

,

…
,

x

N

}

{\displaystyle \scriptstyle \{x_{1},\,x_{2},\,\ldots ,\,x_{N}\}}

 are the observed values of the sample items and

x
¯

{\displaystyle \scriptstyle {\overline {x}}}

 is the mean value of these observations, while the denominator N stands for the size of the sample: this is the square root of the sample variance, which is the average of the squared deviations about the sample mean.

text:
This is a consistent estimator (it converges in probability to the population value as the number of samples goes to infinity), and is the maximum-likelihood estimate when the population is normally distributed.[citation needed] However, this is a biased estimator, as the estimates are generally too low. The bias decreases as sample size grows, dropping off as 1/N, and thus is most significant for small or moderate sample sizes; for

N
>
75

{\displaystyle N>75}

 the bias is below 1%. Thus for very large sample sizes, the uncorrected sample standard deviation is generally acceptable. This estimator also has a uniformly smaller mean squared error than the corrected sample standard deviation.

text: Corrected sample standard deviation[edit]

text: If the biased sample variance (the second central moment of the sample, which is a downward-biased estimate of the population variance) is used to compute an estimate of the population's standard deviation, the result is

text: Here taking the square root introduces further downward bias, by Jensen's inequality, due to the square root being a concave function. The bias in the variance is easily corrected, but the bias from the square root is more difficult to correct, and depends on the distribution in question.

text: An unbiased estimator for the variance is given by applying Bessel's correction, using N − 1 instead of N to yield the unbiased sample variance, denoted s2:

text:
This estimator is unbiased if the variance exists and the sample values are drawn independently with replacement. N − 1 corresponds to the number of degrees of freedom in the vector of deviations from the mean,

(

x

1

−

x
¯

,

…
,

x

n

−

x
¯

)
.

{\displaystyle \scriptstyle (x_{1}-{\overline {x}},\;\dots ,\;x_{n}-{\overline {x}}).}

text: Taking square roots reintroduces bias (because the square root is a nonlinear function, which does not commute with the expectation), yielding the corrected sample standard deviation, denoted by s:

text:
As explained above, while s2 is an unbiased estimator for the population variance, s is still a biased estimator for the population standard deviation, though markedly less biased than the uncorrected sample standard deviation. This estimator is commonly used and generally known simply as the "sample standard deviation". The bias may still be large for small samples (N less than 10). As sample size increases, the amount of bias decreases. We obtain more information and the difference between

1
N

{\displaystyle {\frac {1}{N}}}

 and

1

N
−
1

{\displaystyle {\frac {1}{N-1}}}

 becomes smaller.

text: Unbiased sample standard deviation[edit]

text: For unbiased estimation of standard deviation, there is no formula that works across all distributions, unlike for mean and variance. Instead, s is used as a basis, and is scaled by a correction factor to produce an unbiased estimate. For the normal distribution, an unbiased estimator is given by s/c4, where the correction factor (which depends on N) is given in terms of the Gamma function, and equals:

text: This arises because the sampling distribution of the sample standard deviation follows a (scaled) chi distribution, and the correction factor is the mean of the chi distribution.

text: An approximation can be given by replacing N − 1 with N − 1.5, yielding:

text: The error in this approximation decays quadratically (as 1/N2), and it is suited for all but the smallest samples or highest precision: for n = 3 the bias is equal to 1.3%, and for n = 9 the bias is already less than 0.1%.

text: For other distributions, the correct formula depends on the distribution, but a rule of thumb is to use the further refinement of the approximation:

text: where γ2 denotes the population excess kurtosis. The excess kurtosis may be either known beforehand for certain distributions, or estimated from the data.[citation needed]

text: Confidence interval of a sampled standard deviation[edit]

text: The standard deviation we obtain by sampling a distribution is itself not absolutely accurate, both for mathematical reasons (explained here by the confidence interval) and for practical reasons of measurement (measurement error). The mathematical effect can be described by the confidence interval or CI. To show how a larger sample will make the confidence interval narrower, consider the following examples: A small population of N = 2 has only 1 degree of freedom for estimating the standard deviation. The result is that a 95% CI of the SD runs from 0.45 × SD to 31.9 × SD; the factors here are as follows:

text:
where

q

p

{\displaystyle q_{p}}

 is the p-th quantile of the chi-square distribution with k degrees of freedom, and

1
−
α

{\displaystyle 1-\alpha }

 is the confidence level. This is equivalent to the following:

text:
With k = 1,

q

0.025

=
0.000982

{\displaystyle q_{0.025}=0.000982}

 and

q

0.975

=
5.024

{\displaystyle q_{0.975}=5.024}

. The reciprocals of the square roots of these two numbers give us the factors 0.45 and 31.9 given above.

text: A larger population of N = 10 has 9 degrees of freedom for estimating the standard deviation. The same computations as above give us in this case a 95% CI running from 0.69*SD to 1.83*SD. So even with a sample population of 10, the actual SD can still be almost a factor 2 higher than the sampled SD. For a sample population N=100, this is down to 0.88*SD to 1.16*SD. To be more certain that the sampled SD is close to the actual SD we need to sample a large number of points.

text: These same formulae can be used to obtain confidence intervals on the variance of residuals from a least squares fit under standard normal theory, where k is now the number of degrees of freedom for error.

text: Identities and mathematical properties[edit]

text: The standard deviation is invariant under changes in location, and scales directly with the scale of the random variable. Thus, for a constant c and random variables X and Y:

text: The standard deviation of the sum of two random variables can be related to their individual standard deviations and the covariance between them:

text:
where

var

=

σ

2

{\displaystyle \scriptstyle \operatorname {var} \,=\,\sigma ^{2}}

 and

cov

{\displaystyle \scriptstyle \operatorname {cov} }

 stand for variance and covariance, respectively.

text: The calculation of the sum of squared deviations can be related to moments calculated directly from the data. In the following formula, the letter E is interpreted to mean expected value, i.e., mean.

text: The sample standard deviation can be computed as:

text: For a finite population with equal probabilities at all points, we have

text: This means that the standard deviation is equal to the square root of the difference between the average of the squares of the values and the square of the average value. See computational formula for the variance for proof, and for an analogous result for the sample standard deviation.

text: Interpretation and application[edit]

text: A large standard deviation indicates that the data points can spread far from the mean and a small standard deviation indicates that they are clustered closely around the mean.

text: For example, each of the three populations {0, 0, 14, 14}, {0, 6, 8, 14} and {6, 6, 8, 8} has a mean of 7. Their standard deviations are 7, 5, and 1, respectively. The third population has a much smaller standard deviation than the other two because its values are all close to 7. It will have the same units as the data points themselves. If, for instance, the data set {0, 6, 8, 14} represents the ages of a population of four siblings in years, the standard deviation is 5 years. As another example, the population {1000, 1006, 1008, 1014} may represent the distances traveled by four athletes, measured in meters. It has a mean of 1007 meters, and a standard deviation of 5 meters.

text: Standard deviation may serve as a measure of uncertainty. In physical science, for example, the reported standard deviation of a group of repeated measurements gives the precision of those measurements. When deciding whether measurements agree with a theoretical prediction, the standard deviation of those measurements is of crucial importance: if the mean of the measurements is too far away from the prediction (with the distance measured in standard deviations), then the theory being tested probably needs to be revised. This makes sense since they fall outside the range of values that could reasonably be expected to occur, if the prediction were correct and the standard deviation appropriately quantified. See prediction interval.

text: While the standard deviation does measure how far typical values tend to be from the mean, other measures are available. An example is the mean absolute deviation, which might be considered a more direct measure of average distance, compared to the root mean square distance inherent in the standard deviation.

text: Application examples[edit]

text: The practical value of understanding the standard deviation of a set of values is in appreciating how much variation there is from the average (mean).

text: Experiment, industrial and hypothesis testing[edit]

text: Standard deviation is often used to compare real-world data against a model to test the model. For example, in industrial applications the weight of products coming off a production line may need to comply with a legally required value. By weighing some fraction of the products an average weight can be found, which will always be slightly different to the long-term average. By using standard deviations, a minimum and maximum value can be calculated that the averaged weight will be within some very high percentage of the time (99.9% or more). If it falls outside the range then the production process may need to be corrected. Statistical tests such as these are particularly important when the testing is relatively expensive. For example, if the product needs to be opened and drained and weighed, or if the product was otherwise used up by the test.

text: In experimental science, a theoretical model of reality is used. Particle physics conventionally uses a standard of "5 sigma" for the declaration of a discovery.[8][not in citation given] A five-sigma level translates to one chance in 3.5 million that a random fluctuation would yield the result. This level of certainty was required in order to assert that a particle consistent with the Higgs boson had been discovered in two independent experiments at CERN,[9] and this was also the significance level leading to the declaration of the first detection of gravitational waves.[10]

text: Weather[edit]

text: As a simple example, consider the average daily maximum temperatures for two cities, one inland and one on the coast. It is helpful to understand that the range of daily maximum temperatures for cities near the coast is smaller than for cities inland. Thus, while these two cities may each have the same average maximum temperature, the standard deviation of the daily maximum temperature for the coastal city will be less than that of the inland city as, on any particular day, the actual maximum temperature is more likely to be farther from the average maximum temperature for the inland city than for the coastal one.

text: Finance[edit]

text: In finance, standard deviation is often used as a measure of the risk associated with price-fluctuations of a given asset (stocks, bonds, property, etc.), or the risk of a portfolio of assets[11] (actively managed mutual funds, index mutual funds, or ETFs). Risk is an important factor in determining how to efficiently manage a portfolio of investments because it determines the variation in returns on the asset and/or portfolio and gives investors a mathematical basis for investment decisions (known as mean-variance optimization). The fundamental concept of risk is that as it increases, the expected return on an investment should increase as well, an increase known as the risk premium. In other words, investors should expect a higher return on an investment when that investment carries a higher level of risk or uncertainty. When evaluating investments, investors should estimate both the expected return and the uncertainty of future returns. Standard deviation provides a quantified estimate of the uncertainty of future returns.

text: For example, assume an investor had to choose between two stocks. Stock A over the past 20 years had an average return of 10 percent, with a standard deviation of 20 percentage points (pp) and Stock B, over the same period, had average returns of 12 percent but a higher standard deviation of 30 pp. On the basis of risk and return, an investor may decide that Stock A is the safer choice, because Stock B's additional two percentage points of return is not worth the additional 10 pp standard deviation (greater risk or uncertainty of the expected return). Stock B is likely to fall short of the initial investment (but also to exceed the initial investment) more often than Stock A under the same circumstances, and is estimated to return only two percent more on average. In this example, Stock A is expected to earn about 10 percent, plus or minus 20 pp (a range of 30 percent to −10 percent), about two-thirds of the future year returns. When considering more extreme possible returns or outcomes in future, an investor should expect results of as much as 10 percent plus or minus 60 pp, or a range from 70 percent to −50 percent, which includes outcomes for three standard deviations from the average return (about 99.7 percent of probable returns).

text: Calculating the average (or arithmetic mean) of the return of a security over a given period will generate the expected return of the asset. For each period, subtracting the expected return from the actual return results in the difference from the mean. Squaring the difference in each period and taking the average gives the overall variance of the return of the asset. The larger the variance, the greater risk the security carries. Finding the square root of this variance will give the standard deviation of the investment tool in question.

text: Population standard deviation is used to set the width of Bollinger Bands, a widely adopted technical analysis tool. For example, the upper Bollinger Band is given as x + nσx. The most commonly used value for n is 2; there is about a five percent chance of going outside, assuming a normal distribution of returns.

text: Financial time series are known to be non-stationary series, whereas the statistical calculations above, such as standard deviation, apply only to stationary series. To apply the above statistical tools to non-stationary series, the series first must be transformed to a stationary series, enabling use of statistical tools that now have a valid basis from which to work.

text: Geometric interpretation[edit]

text: To gain some geometric insights and clarification, we will start with a population of three values, x1, x2, x3. This defines a point P = (x1, x2, x3) in R3. Consider the line L = {(r, r, r) : r ∈ R}. This is the "main diagonal" going through the origin. If our three given values were all equal, then the standard deviation would be zero and P would lie on L. So it is not unreasonable to assume that the standard deviation is related to the distance of P to L. That is indeed the case. To move orthogonally from L to the point P, one begins at the point:

text: whose coordinates are the mean of the values we started out with.

text:
[show]Derivation of

M
=
(

x
¯

,

x
¯

,

x
¯

)

{\displaystyle M=({\overline {x}},{\overline {x}},{\overline {x}})}

M

{\displaystyle M}

 is on

L

{\displaystyle L}

 therefore

M
=
(
l
,
l
,
l
)

{\displaystyle M=(l,l,l)}

 with

l
∈

R

{\displaystyle l\in {\textbf {R}}}

The line

L

{\displaystyle L}

 is to be orthogonal to the vector from

M

{\displaystyle M}

 to

P

{\displaystyle P}

. Therefore:

L
⋅
(
P
−
M
)

=
0

(
r
,
r
,
r
)
⋅
(

x

1

−
l
,

x

2

−
l
,

x

3

−
l
)

=
0

r
∗
(

x

1

−
l
+

x

2

−
l
+

x

3

−
l
)

=
0

r
∗
(

∑

i

x

i

−
3
l
)

=
0

∑

i

x

i

−
3
l

=
0

1
3

∑

i

x

i

=
l

x
¯

=
l

{\displaystyle {\begin{aligned}L\cdot (P-M)&=0\\(r,r,r)\cdot (x_{1}-l,x_{2}-l,x_{3}-l)&=0\\r*(x_{1}-l+x_{2}-l+x_{3}-l)&=0\\r*(\sum \limits _{i}x_{i}-3l)&=0\\\sum \limits _{i}x_{i}-3l&=0\\{\frac {1}{3}}\sum \limits _{i}x_{i}&=l\\{\overline {x}}&=l\end{aligned}}}

text:
A little algebra shows that the distance between P and M (which is the same as the orthogonal distance between P and the line L)

∑

i

(

x

i

−

x
¯

)

2

{\displaystyle {\sqrt {\sum \limits _{i}(x_{i}-{\overline {x}})^{2}}}}

 is equal to the standard deviation of the vector x1, x2, x3, multiplied by the square root of the number of dimensions of the vector (3 in this case.)

text: Chebyshev's inequality[edit]

text: An observation is rarely more than a few standard deviations away from the mean. Chebyshev's inequality ensures that, for all distributions for which the standard deviation is defined, the amount of data within a number of standard deviations of the mean is at least as much as given in the following table.

text:
Distance from mean
Minimum population

2

σ

{\displaystyle {\sqrt {2}}\,\sigma }

50%

2σ
75%

3σ
89%

4σ
94%

5σ
96%

6σ
97%

k
σ

{\displaystyle k\sigma }

1
−

1

k

2

{\displaystyle 1-{\frac {1}{k^{2}}}}

[12]

1

1
−
ℓ

σ

{\displaystyle {\frac {1}{\sqrt {1-\ell }}}\,\sigma }

ℓ

{\displaystyle \ell }

text: Rules for normally distributed data[edit]

text: The central limit theorem states that the distribution of an average of many independent, identically distributed random variables tends toward the famous bell-shaped normal distribution with a probability density function of

text: where μ is the expected value of the random variables, σ equals their distribution's standard deviation divided by n1/2, and n is the number of random variables. The standard deviation therefore is simply a scaling variable that adjusts how broad the curve will be, though it also appears in the normalizing constant.

text: If a data distribution is approximately normal, then the proportion of data values within z standard deviations of the mean is defined by:

text:
where

erf

{\displaystyle \scriptstyle \operatorname {erf} }

 is the error function. The proportion that is less than or equal to a number, x, is given by the cumulative distribution function:

text: If a data distribution is approximately normal then about 68 percent of the data values are within one standard deviation of the mean (mathematically, μ ± σ, where μ is the arithmetic mean), about 95 percent are within two standard deviations (μ ± 2σ), and about 99.7 percent lie within three standard deviations (μ ± 3σ). This is known as the 68-95-99.7 rule, or the empirical rule.

text: For various values of z, the percentage of values expected to lie in and outside the symmetric interval, CI = (−zσ, zσ), are as follows:

text:
Confidence
interval
Proportion within
Proportion without

Percentage
Percentage
Fraction

6999674490000000000♠0.674490σ
7001500000000000000♠50%
7001500000000000000♠50%
1 / 7000200000000000000♠2

6999994458000000000♠0.994458σ
68%
32%
1 / 3.125

1σ
7001682689492000000♠68.2689492%
7001317310508000000♠31.7310508%
1 / 7000315148720000000♠3.1514872

7000128155200000000♠1.281552σ
80%
20%
1 / 5

7000164485400000000♠1.644854σ
90%
10%
1 / 10

7000195996400000000♠1.959964σ
95%
5%
1 / 20

2σ
7001954499736000000♠95.4499736%
7000455002640000000♠4.5500264%
1 / 7001219778950000000♠21.977895

7000257582900000000♠2.575829σ
99%
1%
1 / 100

3σ
7001997300204000000♠99.7300204%
6999269979600000000♠0.2699796%
1 / 370.398

7000329052700000000♠3.290527σ
99.9%
0.1%
1 / 7003100000000000000♠1000

7000389059200000000♠3.890592σ
99.99%
0.01%
1 / 7004100000000000000♠10000

4σ
7001999936660000000♠99.993666%
6997633400000000000♠0.006334%
1 / 7004157870000000000♠15787

7000441717300000000♠4.417173σ
99.999%
0.001%
1 / 7005100000000000000♠100000

7000450000000000000♠4.5σ
99.9993204653751%
0.0006795346249%
3.4 / 7006100000000000000♠1000000 (on each side of mean)

7000489163800000000♠4.891638σ
7001999999000000000♠99.9999%
6996100000000000000♠0.0001%
1 / 7006100000000000000♠1000000

5σ
7001999999426697000♠99.9999426697%
6995573303000000000♠0.0000573303%
1 / 7006174427800000000♠1744278

7000532672399999999♠5.326724σ
7001999999900000000♠99.99999%
6995100000000000000♠0.00001%
1 / 7007100000000000000♠10000000

7000573072900000000♠5.730729σ
7001999999990000000♠99.999999%
6994100000000000000♠0.000001%
1 / 7008100000000000000♠100000000

6σ
7001999999998027000♠99.9999998027%
6993197300000000000♠0.0000001973%
1 / 7008506797346000000♠506797346

7000610941000000000♠6.109410σ
7001999999999000000♠99.9999999%
6993100000000000000♠0.0000001%
1 / 7009100000000000000♠1000000000

7000646695100000000♠6.466951σ
7001999999999900000♠99.99999999%
6992100000000000000♠0.00000001%
1 / 7010100000000000000♠10000000000

7000680650200000000♠6.806502σ
7001999999999990000♠99.999999999%
6991100000000000000♠0.000000001%
1 / 7011100000000000000♠100000000000

7σ
99.9999999997440%
6990256000000000000♠0.000000000256%
1 / 7011390682215445000♠390682215445

text: Relationship between standard deviation and mean[edit]

text: The mean and the standard deviation of a set of data are descriptive statistics usually reported together. In a certain sense, the standard deviation is a "natural" measure of statistical dispersion if the center of the data is measured about the mean. This is because the standard deviation from the mean is smaller than from any other point. The precise statement is the following: suppose x1, ..., xn are real numbers and define the function:

text: Using calculus or by completing the square, it is possible to show that σ(r) has a unique minimum at the mean:

text: Variability can also be measured by the coefficient of variation, which is the ratio of the standard deviation to the mean. It is a dimensionless number.

text: Standard deviation of the mean[edit]

text: Often, we want some information about the precision of the mean we obtained. We can obtain this by determining the standard deviation of the sampled mean. Assuming statistical independence of the values in the sample, the standard deviation of the mean is related to the standard deviation of the distribution by:

text: where N is the number of observations in the sample used to estimate the mean. This can easily be proven with (see basic properties of the variance):

text: (Statistical Independence is assumed.)

text: hence

text: Resulting in:

text:
It should be emphasized that in order to estimate the standard deviation of the mean

σ

mean

{\displaystyle \sigma _{\text{mean}}}

 it is necessary to know the standard deviation of the entire population

σ

{\displaystyle \sigma }

 beforehand. However, in most applications this parameter is unknown. For example, if a series of 10 measurements of a previously unknown quantity is performed in a laboratory, it is possible to calculate the resulting sample mean and sample standard deviation, but it is impossible to calculate the standard deviation of the mean.

text: Rapid calculation methods[edit]

text: The following two formulas can represent a running (repeatedly updated) standard deviation. A set of two power sums s1 and s2 are computed over a set of N values of x, denoted as x1, ..., xN:

text: Given the results of these running summations, the values N, s1, s2 can be used at any time to compute the current value of the running standard deviation:

text: Where N, as mentioned above, is the size of the set of values (or can also be regarded as s0).

text: Similarly for sample standard deviation,

text: In a computer implementation, as the three sj sums become large, we need to consider round-off error, arithmetic overflow, and arithmetic underflow. The method below calculates the running sums method with reduced rounding errors.[14] This is a "one pass" algorithm for calculating variance of n samples without the need to store prior data during the calculation. Applying this method to a time series will result in successive values of standard deviation corresponding to n data points as n grows larger with each new sample, rather than a constant-width sliding window calculation.

text: For k = 1, ..., n:

text: where A is the mean value.

text:
Note:

Q

1

=
0

{\displaystyle Q_{1}=0}

 since

k
−
1
=
0

{\displaystyle k-1=0}

 or

x

1

=

A

1

{\displaystyle x_{1}=A_{1}}

text: Sample variance:

text: Population variance:

text: Weighted calculation[edit]

text: When the values xi are weighted with unequal weights wi, the power sums s0, s1, s2 are each computed as:

text: And the standard deviation equations remain unchanged. Note that s0 is now the sum of the weights and not the number of samples N.

text: The incremental method with reduced rounding errors can also be applied, with some additional complexity.

text: A running sum of weights must be computed for each k from 1 to n:

text: and places where 1/n is used above must be replaced by wi/Wn:

text: In the final division,

text: and

text: or

text: where n is the total number of elements, and n' is the number of elements with non-zero weights. The above formulas become equal to the simpler formulas given above if weights are taken as equal to one.

text: History[edit]

text: The term standard deviation was first used[15] in writing by Karl Pearson[16] in 1894, following his use of it in lectures. This was as a replacement for earlier alternative names for the same idea: for example, Gauss used mean error.[17]